Bump postcss from 8.4.21 to 8.4.47 (#113)

Bumps [postcss](https://github.com/postcss/postcss) from 8.4.21 to 8.4.47.
- [Release notes](https://github.com/postcss/postcss/releases)
- [Changelog](https://github.com/postcss/postcss/blob/main/CHANGELOG.md)
- [Commits](postcss/postcss@8.4.21...8.4.47)

---
updated-dependencies:
- dependency-name: postcss
  dependency-type: direct:development
...

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package.json

@@ -9,7 +9,7 @@
     "autoprefixer": "^10.4.12",
     "gray-matter": "^4.0.3",
     "markdown-it-container": "^3.0.0",
-    "postcss": "^8.4.18",
+    "postcss": "^8.4.47",
     "tailwindcss": "^3.2.4",
     "vitepress": "^0.22.4",
     "vue-clipboard3": "^2.0.0"